The Trace Metal Research Support Core Laboratory is an established facility in the Columbia University P30 NIEHS Center. The laboratory enables numerous investigators to precisely measure a broad range of metals in biological specimens, including Pb, As, and a host of other metals and metalloproteins. The NIEHS Center budget provides support for instrumentation, service contracts, methods development, and a pilot study analyses, as well as partial support for the laboratory Director and the Laboratory Manager. In the current proposal, three biomedical projects (Projects #1, #3 and #4) require large numbers of trace metal analyses in urine and/or blood samples. Thus, the Core Laboratory requests funding to support the increased personnel and supply costs associated with these services. The analyses to be conducted include blood Pb analyses (Projects #1 and #4), total urinary As analyses (Projects #1, #3 and #4), and urinary inorganic arsenic (InAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) (Projects #3 and #4). Where needed, the Trace Metal Core Laboratory will provide investigators with bar-coded metal-free urine and blood collection tubes. It will also provide for freezer storage of thousands of urine samples to be analyzed in Projects #3 and #4.